WO2012146054A1 - Concealed dangerous articles detection method and device - Google Patents

Concealed dangerous articles detection method and device Download PDF

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Publication number
WO2012146054A1
WO2012146054A1 PCT/CN2012/000513 CN2012000513W WO2012146054A1 WO 2012146054 A1 WO2012146054 A1 WO 2012146054A1 CN 2012000513 W CN2012000513 W CN 2012000513W WO 2012146054 A1 WO2012146054 A1 WO 2012146054A1
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Prior art keywords
terahertz
beam scanning
object
wavelength
beam
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PCT/CN2012/000513
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French (fr)
Chinese (zh)
Inventor
赵自然
王迎新
陈志强
吴万龙
Original Assignee
同方威视技术股份有限公司
清华大学
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Priority to CN201110110590.XA priority Critical patent/CN102759753B/en
Priority to CN201110110590.X priority
Application filed by 同方威视技术股份有限公司, 清华大学 filed Critical 同方威视技术股份有限公司
Publication of WO2012146054A1 publication Critical patent/WO2012146054A1/en

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/17Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infra-red light
    • G01N21/3581Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infra-red light using far infra-red light; using Terahertz radiation
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01JMEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRA-RED, VISIBLE OR ULTRA-VIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/02Details
    • G01J3/0205Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
    • G01J3/0237Adjustable, e.g. focussing
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01VGEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS
    • G01V8/00Prospecting or detecting by optical means
    • G01V8/005Prospecting or detecting by optical means operating with millimetre waves, e.g. measuring the black losey radiation
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using infra-red, visible or ultra-violet light
    • G01N21/17Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infra-red light
    • G01N21/3563Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infra-red light for analysing solids; Preparation of samples therefor

Abstract

A concealed dangerous articles detection method comprises: terahertz imaging on a measured object (S11); determining whether a suspicious area with the concealed dangerous articles exists or not in the terahertz images of the measured object obtained by terahertz imaging (S12); analyzing the suspicious area with the concealed dangerous articles with multi-wavelength spectrum analysis (S13); identifying whether the suspicious area contains the dangerous articles according to the measurement results of multi-wavelength spectrum analysis (S14); and outputting the terahertz images of the measured object and the detection results of the dangerous articles (S15). Also disclosed is a device for implementing the concealed dangerous articles detection method. The concealed dangerous articles detection method and device can identify the concealed dangerous articles from the perspective of both shape features and material composition, and greatly improve the detection accuracy.

Description

Hiding field detection method and apparatus of dangerous goods

The present invention belongs to the terahertz sensing (terahertz sens ing) technology, and more particularly, to a method and apparatus for an active and continuous-wave terahertz imaging multi-wavelength spectroscopy hidden dangerous goods and identify the remotely located through. Background technique

Explosives Detection much attention in the field of public safety, to explore the fast and effective detection techniques for the protection of lives and property of the people, building a harmonious society has a special significance. With the intensified anti-terrorism measures and enhanced security EOD, Explosive existing close examination and identification equipment is playing a huge role. However, criminals in the sense of growing anti-detection, explosive devices also changes, dangerous goods likely to explode in the inspection stage, pose a security threat to the inspectors and equipment, and therefore the best means of detection is implemented in the distance.

Currently the detection of explosives satisfy demand distance to some extent technologies include X-ray backscatter imaging, laser spectroscopy, thermal imaging, millimeter wave and terahertz technology (Tang 1. proceeds, Shao Jie. Explosives Detection Technology remote Research and application of China security, 2009, 9: 40-45). X-ray backscatter imaging backscatter X-ray imaging of the object to be detected, the use of X-ray energy is low relative to fluoroscopic imaging, the potential detection range of 15 meters, and can be distinguished from the background area of ​​explosives, However, due to ionizing X-rays have sex, there is a certain degree of harm to human health. Laser Laser spectroscopy detection object using primarily absorbed or emitted when irradiated with laser light of certain wavelengths to determine whether explosives, such as Raman spectroscopy, laser induced fluorescence light versed in the presence and Photoacoustic Spectroscopy, laser advantage of this technique is that having a good transmission property, the demand for remote detection, limitation is not pass through the laser opaque objects, and thus can not detect concealed explosives. Thermal imaging technology is the use of a temperature difference between the surface of the hidden object to detect, at this detecting technique bomber significant advantages, but other sources of heat and air flow will impact on the detection results, while the technology can only provide hidden object shape information, is difficult to identify from the viewpoint of explosive material composition, and thus the limited detection ability. Transmitting the millimeter wave technology itself or an object by detecting the millimeter wave band electromagnetic radiation reflected by the imaged object, the millimeter wave has a good penetration of air and the laundry, it is possible to detect concealed weapons distance, but does not have the identification of substances ability. Generally it refers to terahertz radiation within a frequency range of 0.1-10 THz electromagnetic wave, which has several unique characteristics are as follows: Firstly, many organic molecules having a characteristic absorption and dispersion in the THz frequency, so that the substance THz spectroscopy showed "fingerprint ,, secondly, terahertz radiation for many non-metallic ,, polar substance has a strong penetrating power, can directly detect hidden dangerous goods; in addition, THz no X-ray ionizing nature, will not material and human damage, so the THz technology has good prospects in explosives detection.

In 2006 the US Army RDECOM CERDEC Night Vision and Electronic Sensors Laboratory developed a can detect hidden weapons 640 GHz active Imager (2. EL Jacobs, S. Moyer, CC Franck, et al. Concealed weapon identification using terahertz imaging sensors . Pro of SPIE, 2006, 6212: 62120J), the detection distance of about 1.5 m, confocal imaging modality used to ensure high resolution and signal to noise ratio, but the scanning speed is slow. At the same time, the German Aerospace Research Center for Counter-Terrorism needs to carry out terahertz imaging studies used to hide the metal body of dangerous goods under clothing long distance, and the successful development of an operating frequency of 0.8 THz in 2007, detection range up to 20 m, Resolution Less than 2 cm prototype imaging system (3. H.-W. H u bers, AD Semenov, H. Richter, et al Terahertz imaging system for stand-off detection of threats Proc of SPIE, 2007, 6549:.. 65490A ), and can achieve near real-time scanning speed image acquisition. More studies show that using active terahertz imaging to locate suspicious object distance is feasible, but the need for explosives detection joint spectral information be identified, and these studies still in the laboratory stage inside, did not really put into practical application in, to be further developed.

Domestic and international long-distance study of terahertz spectroscopy are few and are at the exploratory stage. 2006 US RPI Terahertz Research Center, use of explosives sample traditional time-domain terahertz spectroscopy to detect distant spread to 30 m distance is still observed RDX peak of 0.82 THz absorption, preliminary indication of long-range identification of explosives is feasible (4. H. Zhong, A. Redo, Y. Chen, et al THz wave standoff detection of explosive materials Proc of SPIE, 2006, 6212:... 62120L), but that the atmospheric absorption spectrum of a serious distortion, signal to noise ratio than poor, is not conducive to practical application. The unit also proposed a new technology of plasma generating pulsed terahertz radiation induced air through the femtosecond laser (5. J. Dai and X.-C. Zhang. Terahertz wave generation from gas plasma using a phase compensator with attosecond phase-control .. accuracy Appl Phys Lett, 2009, 94:.. 021 1 17), so that good transmission of visible light may be transmitted to the remote object to be measured near the terahertz radiation in the atmosphere, the atmosphere in order to avoid causing THz radiation attenuation, spectral analysis and identification of explosives, but the remote detection of the reflected signal also face difficulties, and only a simple spectral analysis techniques for a measurement point of an object is detected, does not have the spatial orientation, it is necessary in conjunction with imaging techniques to meet the practical application. SUMMARY

In order to overcome the above-described deficiencies present in the prior art, the present invention proposes a new method for remote detection of dangerous goods hidden, the core of the method is based on the high frequency tuning and power continuous wave terahertz radiation, first terahertz reflecting the image shape information quickly locate suspicious object, and the selection of certain atmospheric transmission frequency band with good terahertz spectral resolution measurements to further identify the presence of dangerous goods.

The term as used in this application, the "distance" is defined as a general approximately 5 meters from the object - the range of 20 meters. However, the apparatus and method of the present invention are equally applicable to the detection of closer or more distant hidden dangerous goods.

Aspect of the present invention in the following manner:

A method for detecting dangerous hide, the method comprising the steps of: the measured terahertz imaging objects; any suspicious areas in possession of dangerous goods obtained by the object determination terahertz imaging THz image ; suspicious area in possession of dangerous goods is a multi-wavelength measurement of spectral analysis, discriminating whether the suspect area containing dangerous the multi-wavelength spectroscopy measurement results; and an output image and the object to be measured terahertz detection result dangerous.

According to one aspect of the method steps of the present invention, the performing terahertz imaging of the object may comprise: adjusting the terahertz emitter operating at an imaging wavelength; terahertz radiation terahertz transmitter output collimating, focusing, and transferred to the object; collecting terahertz radiation reflected by the object back through the terahertz detector, to obtain information of a measured object pixel; beam scanning control system and by each terahertz beam scanning Perspective pixel, thereby obtaining a terahertz reflection image of the object.

According to another aspect of the method steps of the present invention, any suspicious areas in possession of dangerous goods of the object is determined by the obtained terahertz imaging THz image may include: a terahertz reflection image based on the data acquisition and processing system shape characteristics and gray scale value obtained for suspicious region feature judging possession of dangerous goods in the scanned image, while the precise positioning of the suspicious area.

According to yet another aspect of the method steps of the present invention, in possession of suspicious region dangerous goods multiple wavelength spectroscopic measurement may further include selecting a point of interest within the suspect areas, the multi-wavelength light point of interest Public analytical measurements, too Heziduobo establish long reflection spectrum recognition model, the step pattern recognition method for identifying whether a hazard exists according to another aspect of the method of the present invention, the adjustment within the suspicious area terahertz emitter operating at an imaging wavelength may further comprising: a) a good frequency transmission characteristics of terahertz radiation transmission window in the atmosphere selected according to the determined operating wavelength range terahertz radiation; b) a comprehensive analysis of terahertz radiation transmission power, signal to noise ratio and wavelength imaging Effect of spatial resolution, taking into account the said step a) defined wavelength range, the wavelength of the optimum image.

According to another aspect of the method of the present invention, the control system may include a beam scanning terahertz beam scanning device and a terahertz beam scanning control unit, the control system of the scanning beam by each pixel terahertz beam scanning Perspective the step may further comprise: a terahertz beam scanning control unit sends a signal to the terahertz beam scanning device, adjustment of the terahertz beam scanning apparatus in a beam scanning module to change a terahertz beam spot on the object to be measured position.

According to a further aspect of the method of the present invention, the module may be a beam scanning galvanometer. According to a further aspect of the method of the present invention, the control system may include a beam scanning terahertz beam scanning device and a terahertz beam scanning control unit, the control system of the scanning beam by each pixel terahertz beam scanning Perspective It may further comprise the step of: scanning the terahertz device carrier beam comprises the terahertz transmitter, the terahertz detector system and the terahertz optical assembly is a translational movement, the terahertz beam scanning control unit transmits signal to the terahertz beam scanning device, adjusting the spatial position of the assembly to change the incident terahertz beam spot position on the measured object.

According to a further aspect of the method of the present invention, the step of the suspicious area in possession of dangerous goods multi-wavelength spectroscopic measurement can further include selectively adjusting the wavelength of the terahertz radiation emitter by the wavelength tuning control unit, the terahertz transmitters operating in the desired wavelength multi-wavelength spectroscopy at.

Kind of dangerous goods hidden detecting apparatus, the apparatus comprising: a terahertz emitter means generates a terahertz emitter means for irradiating the object with the object interaction wavelength tunable continuous-wave terahertz radiation; terahertz detector, the terahertz detector for receiving radiation reflected terahertz back by the object to be measured; terahertz optical assembly, the terahertz optical assembly for collimating the beam generating means terahertz emitter, focusing to the object, while the object beam reflected terahertz collected to the terahertz detector; beam scanning control system, said control system for adjusting the beam scan on the spatial position of a terahertz wave beam incident on the object ; and a data acquisition and processing system, said data acquisition and processing system and the terahertz transmitting means, coupled to said detector and said terahertz beam scanning control system for controlling the device emitting device terahertz , coordination terahertz detector, the control beam scanning system, the object constructed terahertz Shot image, based on the shape feature value and the gradation characteristics derived from the reflected terahertz determines whether image possession suspicious region dangerous goods terahertz reflection image of the measured object, the locating suspicious areas to search, then the suspicious region multi-wavelength spectral data of interest within the measuring points are analyzed and processed, and the recognition result is given dangerous.

According to one aspect of the apparatus of the present invention, the transmitting means may include a terahertz terahertz transmitter unit and a wavelength tuning control, said control means tuning the wavelength of the terahertz emitter connected to the emitter of terahertz the radiation wavelength is selectively adjusted.

According to another aspect of the invention apparatus, the terahertz transmitter may be a Gunn oscillator and a frequency multiplier, BWO, parametric oscillator, or a quantum cascade laser.

According to another aspect of the invention apparatus, the terahertz detector may be a Schottky diode, a superconducting - insulator - superconductor junction mixer, or measuring bolometer.

According to yet another aspect of the apparatus of the present invention, the control system includes a beam scanning terahertz beam scanning device and a terahertz beam scanning control unit, the terahertz beam scanning control unit of the terahertz beam scanning device is connected to the said terahertz beam scanning apparatus comprises a beam scanning module, real-time monitoring and adjusting the beam scanning module by means of said THz beam scanning, beam space to complete the setting and reading the position information.

According to yet another aspect of the apparatus of the present invention, the module may be a beam scanning galvanometer. According to yet another aspect of the apparatus of the present invention, the terahertz beam scanning device may comprise a carrying means terahertz emitter, the terahertz detector system and the terahertz optical assembly for a test object for two Pixel-dimensional image of the object scanned to acquire mechanical translation stage.

According to yet another aspect of the apparatus of the present invention, the terahertz optical assembly may include a charge of the collimated terahertz emitter beam generating means and reflected by the object back to the terahertz beam collected terahertz detector beam splitter, mirror and focusing the terahertz wave beam to a parabolic mirror or an ellipsoidal mirror or a lens on the object.

As a result of the above-described methods and structures, the present invention has advantages over the prior art in the following aspects:

1) The method proposed by the present invention is a continuous-wave terahertz imaging and spectroscopy long continuous Boduo Bo which can achieve a combination of characteristics from the shape and angle of view of material composition other dangerous goods hidden ij, detection accuracy is greatly increased;

2) device proposed by the invention to quickly locate the suspicious region may be in possession of dangerous goods by terahertz imaging, and select only the region of a point of interest identification further spectroscopic analysis, spectroscopic imaging is not required for the entire scanning region thus measurement speed, can greatly improve the detection efficiency;

3) continuous length Bo Duobo spectroscopic methods employed in the present invention can avoid the impact of atmospheric absorption, to ensure the feasibility of remote detection, the proposed device and a wavelength tunable continuous wave terahertz radiation, with common pulse compared source that outputs a high average power, and thus a good penetration of the blocking material, high SNR practical. BRIEF DESCRIPTION

From the following detailed description of the drawings The above features and advantages of the invention will become apparent, wherein:

Schematic structural diagram of FIG. 1 THz imaging using multi-wavelength spectroscopy, and remote sensing of explosives first embodiment of the apparatus;

FIG 2 is the atmospheric transmittance of terahertz radiation spectrum (standard atmospheric pressure, temperature of 20 ° C, 40% relative humidity, the transmission distance of 20 m);

FIG 3 is a schematic view of a terahertz beam scanning;

FIG 4 is a schematic diagram of a terahertz image location and identification of suspicious areas;

FIG 5 is explosive RDX sample points and absorption spectra terahertz selected multi-wavelength spectroscopy;

6 is a flowchart according to the first embodiment of the detect hidden explosives embodiment of the present invention; and

FIG 7 is a schematic view of a second embodiment of an apparatus for remote detection of explosives using terahertz imaging and multi-wavelength spectroscopy. DETAILED DESCRIPTION The following detailed description of preferred embodiments of the present invention with reference to the accompanying drawings.

FIG 1 is a schematic diagram of explosives remote sensing apparatus of the first embodiment of terahertz imaging and analyzed using multi-wavelength light praseodymium. As shown, the first advantageous embodiment of the present invention comprises an apparatus 101 terahertz emitter 102 and its wavelength tuning control unit 115, terahertz detector 112; a scanning beam and beam scanning device 105 the control unit 114; too Hz collimating element 104, focusing element 106, the beam splitter 110; and a data acquisition and processing system based on the computer 113. Terahertz emitter 102 and the wavelength tuning control unit 115 constitute a terahertz emitter means capable of generating continuous wave terahertz radiation for irradiating the object with the object interaction wavelength of the tunable. Beam scanning device 105 and beam scanning control unit 114 constitutes a control system for beam scanning. Terahertz collimating element 104, focusing element 106, the beam splitter 110 constitute a terahertz optical assembly for transmitting the radiation beams.

After terahertz emitter 102 with a wavelength of 4 (corresponding to the frequency /.) Continuous wave terahertz radiation 103, traverses the beam splitter 110 and a terahertz collimating element 104 (which may be a parabolic mirror or a lens) to the beam scanning device 105, 105 which follow the propagation direction is controlled by the beam scanning device; focusing element 106 (which may be a parabolic mirror or a lens)] terahertz beam 07 is incident on the object 108 to converge at a particular distance measuring points; manufactured by 109 along the beam propagation path of the incident beam reflected by the object 108 returns, then reflected by the beam splitter 110, the intensity of the beam reflected by the beam 111 is measured by the terahertz detector 112; a data acquisition and processing system 13 reads the specific measurement point is reflected terahertz wave intensity. 114 sends a signal to the control unit beam scanning beam scanning device 105, wherein the mechanical part by a beam scanning device 105 is adjusted to change the incident position of the beam spot 107 on the object 108; 113 and beam data acquisition and processing system scanning control unit 114, terahertz detector 112 coordination obtain the object reflected terahertz wave intensity at different locations within the area to be scanned 108, and finally constructed terahertz reflection image of the object 108. The wavelength tuning control unit 115 of the work wavelength terahertz emitter 102 is adjusted to set the wavelength of the imaging and spectroscopy wavelength ^ W,,.

FIG 2 is a HITRAN atmospheric molecules terahertz radiation within 0, 1-2.5 THz spectral database interval calculated transmission spectra absorption, atmospheric conditions for standard atmospheric pressure, temperature of 20 ° C, 40% relative humidity water vapor, terahertz radiation the transmission distance is assumed to be 20 m. As shown, the attenuation of the transmission spectrum curve 201 shows that two reflected terahertz radiation has a higher frequency range of the transmittance of the transmission window in the atmosphere, such as marked in FIG frequency interval 202 to 208, such as a wavelength tuning control data unit 115 operating wavelength pair 102 were based terahertz emitter set. In the imaging mode, the system operates in a single wavelength 4, can select any frequency value within a wavelength interval corresponding to 202 to 208, of course, necessary to take terahertz emitter output wavelength tuning range; mode in the multi-wavelength spectroscopy, the system operates in a range of wavelengths {Α, Α ,., ^ ϋ, respectively, may be selected in the interval 202 to 208, taking into account the spectral characteristics corresponding to whether the explosives, such as RDX explosive has an absorption peak in the vicinity of 0.8 ΤΗζ, the frequency 204 in the interval (transmission of greater than 80%).

FIG 3 is a schematic view of a terahertz beam scanning. A beam scanning module 301 may comprise two biaxial uniaxial galvano mirror or a galvanometer. 3, the terahertz emitter beam emitted by a parabolic mirror 302 is reflected and collimated by the beam scanning galvanometer module 301 303, 304 after reflection parabolic mirror 305 is incident to, and then focused on the object. Galvanometer 303, 304 may take the form of a plane mirror and is operated under the action of mechanical components in the velocity of the scanning device. About the galvanometer 303 'rotation axis, so that the beam 306 moves in the plane, the incident beam spot position on the object is also moved, to achieve a transverse beam (progressive) scan; galvanometer 304 is located at the focal point of the parabolic mirror 305 ^ about the rotation axis and such that the beam 307 moves in the z-plane, to achieve longitudinal beam (column by column) scan. Beams 308 and 309 corresponding to the scanning galvanometer 304 is rotated at two different angles. By controlling the galvanometer 303 and 304 to achieve coordination terahertz beam pointwise fast scanning, obtaining the final reflection of each pixel in a two-dimensional region of the light intensity measured object.

FIG 4 is a schematic diagram of a terahertz image localization and identification of suspicious areas. 4, after the device according to the present invention is by Lee 101 scan imaging of the object, to obtain a reflection image 401, contains three different regions 402, 403 and 404. Further processing of the image by a computer, the regional analysis, to automatically search for the suspicious area 404, i.e., the region may be in possession of explosives, and select a point 405 inside which a subsequent measurement made based on the shape feature value and the gradation characteristics. Extracting spatial coordinates corresponding to the measuring point, beam scanning means adjusting the beam incident on the light spot on the object is positioned at that point, then multiple wavelength spectroscopic measurement.

Tunable terahertz transmitter within the transmission window shown in FIG output wavelength {Λ ,, ^ ,.,., Λ ^, terahertz measuring reflectance of different wavelengths corresponding to the point of interest 405, thereby obtaining suspect areas multi-wavelength spectral data. Figure 5 shows seven representative samples of RDX terahertz absorption spectrum of 501 and a multi-wavelength spectroscopy selected from 502 to 508, wherein the sampling points 502 to 508 sequentially correspond 0.50, 0.66, 0.86, 1.02, 1.32, 1.50 , 1.99 ΤΗζ, they are in the center of each of the atmospheric transmission window (except for the first point), and can reflect the main spectral features of RDX. Suppose these frequencies are located within the terahertz emitter tunable range, followed by measurement of the reflectance of their corresponding obtain one-dimensional vector of length 7

Figure imgf000011_0001
, And multi-wavelength reflection spectrum as suspect regions. A specific measurement method is to place a reflectance mirror at the object, a record corresponding to the wavelength of the reflected light intensity, referred to as a reference signal, and when detecting a suspicious object, measuring the reflected light intensity at the same wavelength, signal is referred to as an object in the object wavelength reflectivity of r = S ^. Since different wavelengths at different output power terahertz emitter, the degree of attenuation of atmospheric terahertz radiation is different, so the reflectivity is calculated by the reference signal corresponding to the operation of these two factors calibrated.

Next, according to the presence of explosives measured spectrum S identify the suspicious area. This requires a database containing spectra of typical explosive, so first a calibration test sample of typical explosives, and then measuring their multi-wavelength reflection spectrum with the previous step, and all stored as spectral database. On this basis, the use of artificial neural network pattern recognition method or a support vector machine to establish a multi-wavelength spectral recognition model, for determining the type of light praseodymium S Found this model, thereby identifying the presence of explosives area to be analyzed. This completes the mode continuous wave terahertz imaging by the multi-wavelength light language analysis combining hidden explosives remotely located and identified.

6 is a flowchart according to the first embodiment of the detect hidden explosives embodiment of the present invention. 6, first, in step S 10, the user 115 to the work wavelength terahertz emitter 102 is adjusted by tuning the wavelength control means sets the imaging wavelength ^ o.

Then, in step S1 1, 105 by the beam scanning control unit 114 controls a beam scanning device to adjust the position of the terahertz incident beam spot 107 on the object 108, while the data acquisition and processing system 13 reads each of the the intensity of the reflected terahertz wave measuring point, whereby the object capture image 401 reflected terahertz 108.

Next, in step S 12, the image of each region 401 for analysis, because there may be differences in the shape of conventional explosives and explosive objects and object conventional terahertz wave reflection intensity values ​​may be generated and different gray difference image, the shape characteristics derived from the terahertz reflection image 404 and the gradation characteristics based on empirical values ​​is determined whether there may be in possession of explosives suspect areas.

If the judgment is not that the suspicious area, then directly to step S 15, the object image is displayed to the user, and gives the detection result explosives.

If the judgment is that the suspicious area, then at step S 13 further adjusting the operating wavelength of the terahertz emitter 102 is set spectral wavelength ^ A, ..., U, the suspicious region inside the measurement at these wavelengths 404 reflected light intensity at a point 405, multi-wavelength spectral data acquisition. Then, in step S 14, a multi-wavelength spectrum is measured within a substance classes identify suspect areas, comprising determining whether the explosives. Finally, in a terahertz reflection image 15 obtained in step S displayed on the screen, and gives the detection result explosives.

FIG Ί is a schematic view of a second embodiment of the analysis apparatus for remote detection of explosives THz imaging and multi-wavelength light language. 7, a second embodiment of the present invention is advantageous apparatus comprises a terahertz emitter 702 and the wavelength tuning control unit 714, terahertz detector 710; a scanning beam and beam scanning device 712 the control unit 713; terahertz focusing element 704, a beam splitter 708; and a data acquisition and processing computer-based system 711. 702 terahertz emitter and the wavelength tuning control unit 714 constitute a terahertz emitter means capable of generating continuous wave terahertz radiation for irradiating the object with the object interaction wavelength of the tunable. Beam scanning device 712 and beam scanning control unit 713 constitutes a control system for beam scanning. Terahertz focusing element 704 and the beamsplitter 708 constitutes a terahertz optical assembly for transmitting the radiation beams.

Terahertz emitter 702 produces a continuous-wave terahertz radiation 703, after the beam splitter 708 reaches the focusing element 704 (which may be a lens or a parabolic mirror) terahertz beam 705 to converge on the object 706 far from a particular measurement point; 706 reflected by the object beam 707 along the beam propagation path of the incident return of the reflector and then by the beam splitter 708, the intensity of the beam reflected by the beam 709 is measured by the detector 710; a data acquisition and processing system reads 711 to take the specific measurement point is reflected terahertz wave intensity. Carrier system consisting of 712 terahertz beam scanning device emission sources, detectors and other optical components to make a translational movement 701, a beam scanning control unit 713 sends a signal to a beam scanning device 712, the spatial position adjusting system 701 so as to change the incident beam 705 is spot position on the object to be measured 706; Bian data beam scanning control unit 713, coordination terahertz detector 710 and processing system 711 sets and acquires the object at different locations within the scanning area 706 to be reflected terahertz wave intensity, Finally constructed terahertz reflection image of the object 706.

The multi-wavelength spectroscopy substantially the same process and explosives detection flowchart of a second embodiment of the present invention, in the first embodiment, not described herein again.

The above description is only embodiments for realizing the embodiment of the present invention, those skilled in the art will appreciate that any modification or local replacement without departing from the scope of the present invention, all of the claims of the present invention should be defined range. For example, although in the foregoing embodiment of the present invention is directed to apparatus and method for remotely detecting explosives, it is to be understood that: the invention is equally applicable to flammable, explosive, there is Qiang Lie long-range detection method corrosive dangerous goods and equipment. Further, the present invention is also fully applicable to proximity detecting apparatus and method comprising a variety of explosive dangerous goods. Accordingly, the scope of the present invention should be defined by the claims scope of protection as defined prevail.

Claims

Rights request
1. A method for detecting dangerous goods hidden, the method comprising the steps of: imaging the object THz;
Determining whether the suspicious area in possession of dangerous goods of the object obtained by the present terahertz imaging THz image;
Possession of suspicious region dangerous goods multiple wavelength spectroscopic measurement, comprising dangerous according to whether a multi-wavelength spectroscopy identify the suspicious measurement region; and
Output of the object image and the THz detection result dangerous.
2. The method according to claim 1, wherein said terahertz imaging performed for a test object comprising:
Adjusting work terahertz emitter at an imaging wavelength;
The terahertz radiation registration terahertz transmitter output direct, focus, and transmitted to the object;
Collected by the terahertz radiation reflected back by the object terahertz detector, to obtain information of a measured object pixel; and
Control system by beam scanning each pixel terahertz beam scanning field of view, thereby obtaining a terahertz reflection image of the object.
3. The method according to claim 1, wherein the possession of any suspicious region dangerous goods measured object is determined by the obtained terahertz imaging THz image comprising: a data acquisition and processing system based on the reflection of terahertz the image shape characteristics and gray scale value obtained for suspicious region feature judging possession of dangerous goods scanned image, while the precise positioning of the suspicious area.
Step 4. The method according to claim 1, wherein the suspicious region is in possession of dangerous goods multispectral analysis further comprises selecting a measurement wavelength of a point of interest within the suspect areas, the multi-wavelength point of interest spectroscopy measurements, too Heziduobo establish long reflection spectrum recognition model, pattern recognition method for identifying the presence or absence of the suspicious area hazardous
5. The method according to claim 2, wherein said adjusting step terahertz transmitter operating at an imaging wavelength further comprises:
a) the transmission characteristics of terahertz radiation in the atmosphere good frequency selective transmission window according to the determined operating wavelength range terahertz radiation; b) a comprehensive analysis of terahertz radiation transmission power, wavelength and spatial resolution imaging SNR effect, taking into account the said step a) defined wavelength range, the wavelength of the optimum image.
The method according to claim 2, wherein said control system includes a beam scanning terahertz beam scanning device and a terahertz beam scanning control unit, so that the field of view terahertz beam scanning by the beam scanning control system for each pixel point step further comprises: said terahertz beam scanning control unit sends a signal to the terahertz beam scanning device, adjustment of the terahertz beam scanning device to vary the velocity of the scanning module terahertz beam spot on the object to be measured position.
7. The method according to claim 6, wherein said module is a galvanometer beam scanning.
Each pixel 8. The method according to claim 2, wherein said control system includes a beam scanning terahertz beam scanning device and a terahertz beam scanning control unit, so that a terahertz beam scanning the field of view by the beam scanning control system point step further comprises: said terahertz beam scanning apparatus comprising a carrier terahertz emitter, the terahertz detector system and the terahertz optical assembly is a translational movement, the terahertz beam scanning control unit transmits signal to the terahertz beam scanning device, adjusting the spatial position of the assembly to change the incident terahertz beam spot position on the measured object.
Step suspicious region 9. The method according to claim 1, wherein the possession of dangerous goods for multi-wavelength measurement of spectral analysis further includes selectively adjusting the wavelength of the terahertz radiation emitter by the wavelength tuning control unit , the terahertz transmitters operating in the desired wavelength multi-wavelength spectroscopy at.
10. An apparatus for implementing the method of detecting hidden dangerous goods according to claim 1, said apparatus comprising:
Terahertz emitter means generates a terahertz emitter means for irradiating the object with the object interaction wavelength tunable continuous-wave terahertz radiation;
Terahertz detector, the terahertz detector for receiving radiation reflected terahertz back by the object to be measured;
Terahertz optical assembly, the optical assembly for terahertz beam registration apparatus generates the terahertz emitter straight, focused onto the object, while the object beam reflected terahertz collected to the terahertz detector;
Beam scanning control system, said control system for adjusting the beam scan on the spatial position of the terahertz beam incident on the object; and a data acquisition and processing system, said data acquisition and processing system and the terahertz-emitting device, the said detector and said terahertz beam scanning control system connected to control said apparatus terahertz emitting device, coordination terahertz detector, the control beam scanning system, constructed terahertz reflection image of the object, and based on the shape feature values ​​of gradation derived from the characteristic reflection terahertz determines whether image possession of suspicious region dangerous goods terahertz reflection image of the measured object, the locating suspicious areas to search, then the suspicious area of ​​interest within the multi-wavelength spectral data point in the measurement and analysis process, and the recognition result is given dangerous.
1 1. The apparatus of claim 10, wherein said apparatus includes a terahertz emitter and a terahertz emitter wavelength tuning control means, said control means tuning the wavelength of the terahertz emitter connected to said solar Hertz wavelength radiation emitter is selectively tune
"F.
12. The apparatus of claim 1 according to claim 1, wherein said terahertz transmitter is a Gunn oscillator and a frequency multiplier, BWO, parametric oscillator, or a quantum cascade laser.
13. Apparatus according to claim 11, wherein the terahertz detector is a Schottky diode, a superconducting - insulator - superconductor junction mixer, or measuring bolometer.
14. The apparatus according to claim 10, wherein said control system includes a beam scanning terahertz beam scanning device and a terahertz beam scanning control unit, the terahertz beam scanning control unit of the terahertz beam scanning device is connected the terahertz beam scanning apparatus comprises a beam scanning module, real-time monitoring and adjusting the beam scanning module by means of said THz beam scanning, beam space to complete the setting and reading the position information.
15. The apparatus according to claim 14, wherein said module is a beam scanning galvanometer.
16. Apparatus according to claim 14, wherein said terahertz beam scanning apparatus comprising carrying means is said terahertz emitter, the terahertz detector system and the terahertz optical assembly for a test objects two-dimensionally scanned point by point so as to acquire images of the object a mechanical translation stage.
17. The apparatus as claimed in any one of claims 10-16, wherein said optical assembly comprises terahertz responsible for the collimated terahertz emitter beam generating means and the object beam reflected terahertz collected the beam splitter to the terahertz detector, said plane mirror and focusing the terahertz beam parabolic mirror or an ellipsoidal mirror or a lens on the object.
PCT/CN2012/000513 2011-04-29 2012-04-13 Concealed dangerous articles detection method and device WO2012146054A1 (en)

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